During a 2-year period we studied the reproductive and fat body cycles and reproductive characteristics (clutch size, egg size) of the oviparous lizard Acanthodactylus erythrurus in central Spain. Testes exhibited their maximal volume during April -June and decreased in size throughout the summer. Fat bodies of males were smallest during the spring mating period. Vitellogenesis started in May or June, with oviposition occurring during June-July. Female fat bodies declined in size during the period of yolk deposition. A delay in the timing of reproductive events in 1 year was associated with adverse weather conditions during early spring. During the "good" year, reproduction was initiated early enough to allow some females to produce a second clutch. Both clutch size and egg size increased with female body length, but did not vary between years. Environmental factors that induced temporal variation in the timing of reproduction and clutch frequency did not affect clutch characteristics.